U.S. patent number 5,489,618 [Application Number 08/158,507] was granted by the patent office on 1996-02-06 for process for preparing polyurethane foam.
This patent grant is currently assigned to OSi Specialties, Inc.. Invention is credited to Richard M. Gerkin.
United States Patent |
5,489,618 |
Gerkin |
February 6, 1996 |
Process for preparing polyurethane foam
Abstract
A process for preparing a polyurethane foam according to the
one-shot foaming process by reactions between a polyisocyanate and
an active hydrogen-containing component including water and an
organic polyol wherein said reactions are conducted in the presence
of a salt of a tertiary amine and a carboxylic acid having hydroxyl
functionality.
Inventors: |
Gerkin; Richard M. (Cross
Lanes, WV) |
Assignee: |
OSi Specialties, Inc. (Danbury,
CT)
|
Family
ID: |
22568451 |
Appl.
No.: |
08/158,507 |
Filed: |
November 29, 1993 |
Current U.S.
Class: |
521/128; 521/130;
521/118; 521/117; 521/173; 521/157; 521/172; 521/164; 521/170;
521/129 |
Current CPC
Class: |
C23F
11/10 (20130101); C23F 11/143 (20130101); C23F
11/08 (20130101); C08G 18/1875 (20130101); C08G
2110/005 (20210101); C08G 2110/0083 (20210101); C08G
2110/0025 (20210101); C08G 2110/0008 (20210101) |
Current International
Class: |
C08G
18/18 (20060101); C08G 18/00 (20060101); C08J
009/08 (); C08G 018/18 () |
Field of
Search: |
;521/117,118,129,130,157,170,172,173,128,164,128 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
|
651638 |
|
Nov 1962 |
|
CA |
|
0088377 |
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Sep 1983 |
|
EP |
|
0140480 |
|
May 1985 |
|
EP |
|
0276956 |
|
Aug 1988 |
|
EP |
|
0361937 |
|
Apr 1990 |
|
EP |
|
0484749 |
|
May 1992 |
|
EP |
|
0585636 |
|
Mar 1994 |
|
EP |
|
879167 |
|
Oct 1961 |
|
GB |
|
1541593 |
|
Mar 1979 |
|
GB |
|
Other References
Fondots, "Developments in Amine Catalysts for Urethane Foam", J.
Cellular Plastics, Oct., 1975, pp. 250-255..
|
Primary Examiner: Seidleck; James J.
Assistant Examiner: Sergent; Rabon
Attorney, Agent or Firm: Banner & Allegretti, Ltd.
Claims
I claim:
1. In a process for preparing a polyurethane foam according to the
one-shot foaming process by reactions between a polyisocyanate and
an active hydrogen-containing component including water and an
organic polyol in the presence of a catalyst, a surfactant and
optional crosslinker, the improvement comprising conducting said
reactions in the presence of a salt which consists of a tertiary
amine reacted with a carboxylic acid having hydroxyl functionality
as a catalyst; wherein the tertiary amine is selected from the
group consisting of bis (N,N-dimethylaminoethyl)ether;
1,4-diazabicyclo[2.2.2]octane and mixtures thereof, and wherein the
carboxylic acid has the formula:
wherein R is an at least divalent hydrocarbon moiety having 1 to 20
carbon atoms, m and n are integers each separately having a value
of at least 1.
2. The process of claim 1 wherein said hydrocarbon moiety is
selected from the group consisting of a linear aliphatic
hydrocarbon moiety, a branched aliphatic hydrocarbon moiety, an
alicyclic aliphatic hydrocarbon moiety and an aromatic hydrocarbon
moiety.
3. The process of claim 2 wherein said carboxylic acid having
hydroxyl functionality is selected from the group consisting of
citric acid, dimethylolpropionic acid, 2-hydroxymethylpropionic
acid, salicylic acid, m-hydroxy benzoic acid, p-hydroxyl benzoic
acid, glycolic acid, .beta.-hydroxybutyric acid, cresotic acid,
3-hydroxy-2-naphthoic acid, lactic acid, tartaric acid, malic acid,
resorcylic acid, hydroferulic acid and mixtures thereof.
4. The process of claim 3 wherein said reactions are conducted in
the presence of a polyurethane foam additive selected from the
group consisting of an amine catalyst, an organo-metallic catalyst,
a metal salt catalyst, a crosslinker, a silicone surfactant, an
organic blowing agent and mixtures thereof.
5. The process of claim 1 wherein said reactions are conducted in
the presence of a polyurethane foam additive selected from the
group consisting of an amine catalyst, an organo-metallic catalyst,
a metal salt catalyst, a crosslinker, a silicone surfactant, an
organic blowing agent and mixtures thereof.
6. In a process for preparing a polyurethane foam according to the
one-shot foaming process by reactions between a polyisocyanate and
an active hydrogen-containing component including water and an
organic polyol in the presence of a catalyst, a surfactant and
optional crosslinker, the improvement comprising conducting said
reactions in the presence of a salt which consists of a tertiary
amine reacted with a carboxylic acid having hydroxyl functionality
as a catalyst, said salt being present in an amount sufficient to
reduce foam shrinkage; wherein the tertiary amine is selected from
the group consisting of bis (N,N-dimethylaminoethyl) ether;
1,4-diazabicyclo[2.2.2]octane and mixtures thereof, and wherein the
carboxylic acid has the formula:
wherein R is an at least divalent hydrocarbon moiety having 1 to 20
carbon atoms, m and n are integers each separately having a value
of at least 1.
7. The process of claim 6 wherein said hydrocarbon moiety is
selected from the group consisting of a linear aliphatic
hydrocarbon moiety, a branched aliphatic hydrocarbon moiety, an
alicyclic aliphatic hydrocarbon moiety and an aromatic hydrocarbon
moiety.
8. The process of claim 7 wherein said carboxylic acid having
hydroxyl functionality is selected from the group consisting of
citric acid, dimethylolpropionic acid, 2-hydroxymethylpropionic
acid, salicylic acid, m-hydroxy benzoic acid, p-hydroxyl benzoic
acid, glycolic acid, .beta.-hydroxybutyric acid, cresotic acid,
3-hydroxy-2-naphthoic acid, lactic acid, tartaric acid, malic acid,
resorcylic acid, hydroferulic acid and mixtures thereof.
9. The process of claim 8 wherein said reactions are conducted in
the presence of a polyurethane foam additive selected from the
group consisting of an amine catalyst, an organo-metallic catalyst,
a metal salt catalyst, a crosslinker, a silicone surfactant, an
organic blowing agent and mixtures thereof.
10. The process of claim 6 wherein said reactions are conducted in
the presence of a polyurethane foam additive selected from the
group consisting of an amine catalyst, an organo-metallic catalyst,
a metal salt catalyst, a crosslinker, a silicone surfactant, an
organic blowing agent and mixtures thereof.
11. In a process for preparing a polyurethane foam according to the
one-shot foaming process by reactions between a polyisocyanate and
an active hydrogen-containing component including water and an
organic polyol in the presence of a catalyst, a surfactant and
optional crosslinker, the improvement comprising conducting said
reactions in the presence of a salt which consists of a tertiary
amine reacted with a carboxylic acid having hydroxyl functionality
as a catalyst, said salt being present in an amount sufficient to
reduce the force needed to mechanically crush the foam; wherein the
tertiary amine is selected from the group consisting of bis
(N,N-dimethylaminoethyl) ether; 1,4,-diazabicyclo[2.2.2]octane, and
mixtures thereof, and wherein the carboxylic acid has the
formula:
wherein R is an at least divalent hydrocarbon moiety having 1 to 20
carbon atoms, m and n are integers each separately having a value
of at least 1.
12. The process of claim 11 wherein said hydrocarbon moiety is
selected from the group consisting of a linear aliphatic
hydrocarbon moiety, a branched aliphatic hydrocarbon moiety, an
alicyclic aliphatic hydrocarbon moiety and an aromatic hydrocarbon
moiety.
13. The process of claim 12 wherein said carboxylic acid having
hydroxyl functionality is selected from the group consisting of
citric acid, dimethylolpropionic acid, 2-hydroxymethylpropionic
acid, salicylic acid, m-hydroxy benzoic acid, p-hydroxyl benzoic
acid, glycolic acid, .beta.-hydroxybutyric acid, cresotic acid,
3-hydroxy-2-naphthoic acid, lactic acid, tartaric acid, malic acid,
resorcylic acid, hydroferulic acid and mixtures thereof.
14. The process of claim 11 wherein said reactions are conducted in
the presence of a polyurethane foam additive selected from the
group consisting of an amine catalyst, an organo-metallic catalyst,
a metal salt catalyst, a crosslinker, a silicone suffactant, an
organic blowing agent and mixtures thereof.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a process for producing polyurethane foams
using the one-shot foaming process. The invention specifically
relates to using a salt of a tertiary amine and a carboxylic acid
with hydroxyl functionality as a catalyst for promoting reactions
involved in the production of one-shot polyurethanes, particularly
flexible polyurethane foams.
2. Background
Polyurethane foams are produced by reacting a polyisocyanate with
compounds containing two or more active hydrogens. The active
hydrogen-containing compounds are typically polyols, primary and
secondary polyamines, and water. Two major reactions take place
among these reactams during the preparation of a polyurethane foam.
These reactions must proceed simultaneously and at a competitively
balanced rate during the process in order to yield a polyurethane
foam with desired physical characteristics.
Reaction between the isocyanate and the polyol or polyamine,
usually referred to as the gel reaction, leads to the formation of
a polymer of high molecular weight. This reaction is predominant in
foams blown exclusively with low boiling point organic compounds.
The progress of this reaction increases the viscosity of the
mixture and generally contributes to crosslink formation with
polyfunctional polyols. The second major reaction occurs between
the isocyanate and water. This reaction adds to urethane polymer
growth, and is important for producing carbon dioxide gas which
promotes foaming. As a result, this reaction often is referred to
as the blow reaction.
Both the gel and blow reactions occur in foams blown partially or
totally with carbon dioxide gas. In fact, the in-situ generation of
carbon dioxide by the blow reaction plays an essential part in the
preparation of "one-shot", water blown polyurethane foams.
Water-blown polyurethane foams, particularly flexible foams, are
produced by both molded and slab foam processes.
In order to obtain a good urethane foam structure, the gel and blow
reactions must proceed simultaneously and at optimum balanced
rates. For example, if the carbon dioxide evolution is too rapid in
comparison with the gel reaction, the foam tends to collapse.
Alternatively, if the gel extension reaction is too rapid in
comparison with the blow reaction generating carbon dioxide, foam
rise will be restricted, thus resulting in a high-density foam.
Also, poorly balanced crosslinking reactions will adversely impact
foam stability. In practice, the balancing of these two reactions
is controlled by the nature of the promoters and catalysts,
generally amine and/or organometallic compounds, used in the
process.
Flexible and rigid foam formulations usually include a polyol, a
polyisocyanate, water, optionally a low boiling (highly volatile)
organic blowing agent, a silicone type surfactant, and catalysts.
Flexible foams are generally open-celled materials, while rigid
foams usually have a high proportion of closed cells.
Generally, catalysts for producing polyurethanes are of two general
types: tertiary amines (mono and poly) and organo-tin compounds.
Organometallic tin catalysts predominantly favor the gelling
reaction; while amine catalysts exhibit a more varied range of
blow/gel balance. Using tin catalysts in flexible foam formulations
also increases the quantity of closed cells contributing to foam
tightness. Tertiary amines also are effective as catalysts for the
chain extension reaction and can be used in combination with the
organic tin catalysts. For example, in the preparation of flexible
slabstock foams, the "one-shot" process has been used wherein
triethylenediamine is employed for promoting the water-isocyanate
reaction and the cross-linking reaction; while an organic tin
compound is used in synergistic combination to promote the chain
extension reaction.
Most tertiary amines used for the catalysis of polyurethane foam
forming reactions are of the fugitive type. Fugitive amines are
designated as such because they do not react into the urethane
polymer matrix and remain as low molecular weight compounds in the
polymer. Many prior art fugitive amines impart a strong amine odor
to the polyurethane foam and may present significant safety
problems. The fugitivity of amines results in the emission of fumes
from hot foam in both molded foam and slabstock foam processes.
Airborne amine vapors can be an industrial hygiene problem in foam
production plants. A particular effect of the amine vapor is
glaucopsia also known as blue-haze or halovision. It is a temporary
disturbance of the clarity of vision. There is increasing demand in
the foam production industry for low fugitivity catalysts.
Amines which have a functional group capable of reacting with the
isocyanate are available. These amines are bound to the polymer
matrix during the reaction. Unfortunately, their catalytic activity
normally is limited as compared to the fugitive amines.
Flexible polyurethane foams are commercially prepared as slabstock
foam or in molds. Although some slabstock foam is produced by
pouring the mixed reactants in large boxes, the predominant
industrial process is the continuous production by deposition of
the reacting mixture on a paper lined conveyor. The foam rises and
cures as the conveyor advances and the foam is cut into large
blocks as it exits the foam machine. Some of the uses of flexible
slabstock polyurethane foams include: furniture cushions, bedding,
and carpet underlay. A particular problem occurs when slabstock
foam is produced by the continuous process on a machine with a
short conveyor. The formulation has to be highly catalyzed in order
to be sufficiently cured when the foam reaches the cutting saw.
However, the initiation of the reaction must be delayed to allow
uniform laydown of the reacting mixture. In such situations,
delayed action catalysts potentially can be used to achieve the
required reactivity profile.
The process for making molded foams typically involves the mixing
of the starting materials with polyurethane foam production
machinery and pouring the reacting mixture, as it exits the
mix-head, into a mold. The principal uses of flexible molded
polyurethane foams are: automotive seats; automotive headrests and
armrests; and also in furniture cushions. Some of the uses of
semi-flexible foams include automotive instrument panels, energy
managing foam, and sound absorbing foam.
Modern molded flexible polyurethane foam production processes such
as those used in Just-in-Time (JIT) supply plants have increased
the demand for rapid demold systems. Gains in productivity and/or
reduced part cost result from reduced cycle times. Rapid cure High
Resilience (HR) molded flexible foam formulations typically achieve
demold times of three minutes. This is accomplished by using one or
a combination of the following: a higher mold temperature, more
reactive intermediates (polyols and/or isocyanate), or increasing
the quantity and/or the activity of the catalysts.
High reactivity molded polyurethane systems give rise to a number
of problems, however. The fast initiation times require that the
reacting chemicals be poured into a mold quickly. In some
circumstances a rapid build-up of the viscosity of the rising foam
causes a deterioration of its flow properties and can result in
defects in the molded parts. Additionally, rapidly rising foam can
reach the parting line of the mold cavity before the cover has had
the time to close resulting in collapsed areas in the foam. In such
situations, delayed action catalysts potentially can be used to
improve the initial system flow and allow sufficient time to close
the mold.
Another difficulty experienced in the production of molded foams,
which is usually worse in the case of rapid cure foam formulations,
is foam tightness. Foam tightness is caused by a high proportion of
closed cells at the time the molded foam part is removed from the
mold. If left to cool in that state, the foam part will generally
shrink irreversibly. A high proportion of open cells also are
required if the foam is to have the desired high resiliency.
Consequently, foam cells have to be opened either by physically
crushing the molded part or inserting it in a vacuum chamber. Many
strategies have been proposed, both chemical and mechanical, to
minimize the quantity of closed cells at demold.
The principal uses of rigid polyurethane foam are: pour-in-place
insulation foams for refrigeration applications, transportation
applications, and metal doors, boardstock insulation, and sprayed
insulation. In rigid foam applications, delayed action catalysts
are used for the same reasons needed in flexible foam molding, to
delay the initial system reactivity while offering the short cure
times required for fast productions cycles.
Delayed action catalysts used in the above-described processes are
usually simple amine salts of a tertiary amine and a carboxylic
acid such as formic acid, acetic acid, or 2-ethylhexanoic acid (J.
Cellular Plastics, p. 250-255, September/October, 1975). The salts
are not catalytically active and, as a consequence, the amines do
not activate the reaction until the salt is dissociated by the
increasing temperature of the reacting mixture. Unfortunately,
using carboxylic acid blocked amine catalysts generally has a
tightening effect on the foam (see U.S. Pat. Nos. 3,385,806,
4,701,474, and 4,785,027).
Delayed action catalysts find their main application in the
manufacture of molded flexible polyurethane foam pans. In such
applications, it is desirable to make the molding time as short as
possible ("rapid demold"), but the onset of the reaction must be
delayed so that the viscosity increase accompanying the reaction
does not jeopardize proper mold filling.
One problem specific to the use of delayed action, acid-blocked
catalysts, i.e., acid-amine salts, is the corrosion caused to the
production equipment of the system by such materials. Foam machines
usually produce foam by mixing the isocyanate with a mixture of the
other components of the formulation either through high pressure
impingement or by high speed stirring. The mixture of the
ingredients, save the isocyanate, is collectively called the resin.
The resin usually includes the polyol, water, silicone surfactant,
and the catalysts. Delayed action catalysts are most conveniently
incorporated into the resin directly or as a water/amine salt
premix. The acid-blocked, amine salt catalysts often cause
significant corrosion damage to the mixing and dispensing equipment
used in urethane foam manufacture, particularly the pumps and
mix-head.
There remains a need in the polyurethane industry for catalysts
that have a delayed action; so as to delay the onset of the
isocyanate-polyol reaction, referred to as the "initiation time",
without adversely impacting the time to complete the reaction or
cure, while avoiding some of the other problems common to known
delayed action catalysts.
3. Description of Related Art
The use of acid-grafted polyether polyols as reactivity controllers
for the production of polyurethane foams is disclosed in U.S. Pat.
No. 4,701,474. Such acid-grafted polyether polyols purportedly
reduce the reactivity of polyurethane foam formulations without the
tightening effect which usually results from using carboxylic
acid-amine salts. The number average molecular weight range claimed
for the disclosed acid-grafted polyether polyols is 1,000 to
10,000.
Preparing polyurethane foams in the presence of polyether acids is
disclosed in U.S. Pat. No. 4,785,027. The polyether acids are mono-
or di-acids with the acid functional groups located at the ends of
the polymer chains. The polyether chain is built from ethylene
and/or propylene oxide to have repeating alkoxy groups. In the case
of mono acids, the other terminal group can be an alkyl or hydroxyl
function. The presence of the hydroxyl functional group is
optional. Such polyether acids purportedly delay the initial
reaction rate without increasing foam tightness observed with
formic acid-amine salts.
In U.S. Pat. No. 4,366,084 the fuming of dimethylaminopropylamine
(DMAPA) is reduced by blocking the amine with phenol. The reduction
in fuming increases directly with the percent blocking. According
to the patent, using the DMAPA-phenol salts at varied blocking
ratios does not cause any deterioration in the air flow and
compression set properties of the foam.
U.S. Pat. No. 5,179,131 discloses that the addition of mono- or
dicarboxylic acids to polyurethane foam formulations made using
polyisocyanate polyaddition polymer poly-dispersions results in a
reduction in foam shrinkage. The functional groups attached to the
acid are either alkyl or alkylene.
A process for making open-celled crosslinked foams is disclosed in
U.S. Pat. No. 4,211,849. The crosslinker is a crystalline
polyhydroxy compound having at least 3 hydroxy groups.
The use of the amine salts of tertiary amino-acids as delayed
action catalysts in the production of polyurethanes is disclosed in
U.S. Pat. No. 4,232,152.
The use of particular N-hydroxyalkyl quaternary ammonium
carbonylate salts as delayed action catalysts for the production of
polyurethane is disclosed in U.S. Pat. Nos. 4,040,992 and
4,582,861.
The use of particular aliphatic tertiary monoamines, and the
carboxylic acid salts thereof as catalysts, in the production of
polyurethane foam is disclosed in U.S. Pat. Nos. 4,450,246 and
4,617,286 and in Canadian Pat. 651,638. A variety of organic mono
or dicarboxylic acids are disclosed. Canadian Pat. 651,638, in
particular, describes preparing polyurethane foams from a
isocyanate-terminated polytetramethyleneether or polypropyleneether
polyurethane prepolymer and water, in the presence of an acid-amine
salt. In certain examples, salts of the hydroxy-acid, citric acid
and either N-methyl morpholine and triethylamine are specifically
exemplified.
DETAILED DESCRIPTION
The present invention is based on the discovery that the amine salt
formed by reaction between a tertiary amine and a carboxylic acid
having hydroxyl functional groups ("hydroxy acids") can be used as
a delayed action catalyst for producing polyurethane foams using
the one-shot foaming process and that the use of such amine salt
catalyst offers significant processing advantages over conventional
delayed action catalysts.
Use of the amine salts of the "hydroxy acids" in the one-shot
foaming technique unexpectedly results in the production of
flexible polyurethane foams which either are more open or more
easily opened, or both and have a significantly reduced tendency to
shrink. Physical properties of foam made using such catalysts,
particularly tear resistance, are improved by the use of the
hydroxy acid salts. The amine salts prepared from the disclosed
hydroxy acids also are much less corrosive than amine salts
prepared from the commonly used carboxylic acids, such as formic
acid; acetic acid; and 2-ethylhexanoic acid. Additionally,
evolution of amine vapors from foams made with the amine salts of
the disclosed hydroxy acids is unexpectedly lower than that
experienced by foams made with the commonly used amine-acid
salts.
This invention relates to a process for making flexible
polyurethane foams and rigid polyurethane foams using the one shot
foaming approach. In accordance with the present invention, the
polyurethane reaction kinetics are controlled by including in the
foaming mixture a delayed-action catalyst comprising the amine salt
of a tertiary amine and a carboxylic acid having one or more
hydroxyl functional groups. The polyurethane manufacturing process
of the present invention typically involves the reaction of: an
organic polyisocyanate; a polyol generally having a hydroxyl number
from about 10 to about 600 and one or more tertiary amine
catalysts, at least one of which is the amine salt of a tertiary
amine and a hydroxy-carboxylic acid. In addition to the previously
indicated materials, flexible foam formulations also generally
include: water; an optional organic low boiling auxiliary blowing
agent; a silicone surfactant; tin catalyst, and a crosslinker(s)
for stabilization or hardening. Rigid foam formulations often
contain both a low boiling organic material and water for
blowing.
The "one shot foam process" for making polyurethane foam is a
one-step process in which all of the ingredients necessary for
producing the foamed polyurethane product including the
polyisocyanate, the organic polyol, water, catalysts, surfactant
optional organic blowing agent and the like are simply blended
together, poured onto a moving conveyor or into a mold of a
suitable configuration and cured. The one shot process is to be
contrasted with the prepolymer process wherein a liquid prepolymer
adduct of a polyisocyanate and a polyol normally having terminal
isocyanate groups first is prepared in the absence of any
foam-generating constituents and then the prepolymer is reacted
with water in the presence of catalyst in a second step to form the
solid urethane polymer.
Carboxylic acids useful for preparing the amine salts according the
subject invention have the general formula:
Where
R is an at least divalent hydrocarbon moiety, typically an at least
divalent linear or branched aliphatic hydrocarbon moiety and/or an
at least divalent alicyclic or aromatic hydrocarbon moiety.
n is an integer having a value of at least 1 and allows for mono
and polyhydroxy substitution on the hydrocarbon moiety.
m is an integer having a value of at least 1 and allows for mono
and polycarboxyl substitution on the hydrocarbon moiety.
The "at least divalent hydrocarbon moiety" can be a saturated or
unsaturated moiety of 1 to 20 carbon atoms, including a linear
aliphatic moiety, a branched aliphatic moiety, an alicyclic moiety
or an aromatic moiety. Stated otherwise, R can, for example, be a
linear, or branched alkylene group of one to 10 carbon atoms, a
cyclic alkylene group of 4 to 10 carbon atoms, or an arylene, an
alkarylene, or an aralkylene group of 6 to 20 carbon atoms.
Specific non-limiting examples of suitable hydrocarbon moieties are
methylene, ethylene, n-propylene, iso-propylene, n-butylene,
isobutylene, n-amylene, n-decylene, 2-ethylhexylene, o-, m-,
p-phenylene, ethyl-p-phenylene 2,5-naphthylene, p,p'-biphenylene,
cyclopentylene, cycloheptylene, xylylene, 1,4-dimethylenephenylene
and the like. While above-noted radicals have two available
substitution sites, at least one for a carboxyl group and one for a
hydroxyl group, it is contemplated that additional hydrogens on the
hydrocarbon could be replaced with further hydroxyl and/or carboxyl
groups. The following hydroxy acids are illustrative of compounds
suitable for practicing the present invention: citric acid,
dimethylolpropionic acid, 2-hydroxymethylpropionic acid, salicylic
acid, m-hydroxy benzoic acid, p-hydroxyl benzoic acid,
dihydroxybenzoic acid, glycolic acid, .beta.-hydroxybutyric acid,
cresotic acid, 3-hydroxy-2-naphthoic acid, lactic acid, tartaric
acid, malic acid, resorcylic acid, hydroferulic acid and the like.
Lactones (cyclic esters) wherein a hydroxyl group and a carboxyl
group on the same molecule of the above formula react with one
another to form a hydroxy acid suitable for practicing the present
invention also can be used. Such lactones include
gamma-butyrolactone. Hydroxy-acids useful in the practice of the
present invention generally have molecular weights below about
250.
The literature includes many examples of reactive tertiary amine
catalysts which potentially can form part of the urethane polymer.
The reactive group usually is a hydroxyl function which adds to an
isocyanate group. Other functional groups containing active
hydrogens also can be considered to achieve that purpose. In
contrast to such tertiary amines, the reactive group in the
disclosed amine salts of hydroxy-acids is on the acid rather than
on the amine.
Tertiary amines used to form an amine salt with the above-described
hydroxy-acids can be any of the tertiary amines used for catalyzing
the reactions of isocyanate with compounds containing active
hydrogens. Suitable tertiary amines include dimethyl benzylamine,
trimethylamine, triethanolamine, N-diethylethanolamine, N-methyl
pyrrolidone, N-vinyl pyrrolidone, N-methyl morpholine, N-ethyl
morpholine, dimethylcyclohexylamine (DMCHA), N,N,N',N",
N"-pentamethyldiethylenetriamine, and the like. Preferred amines
include bis(N,N-dimethylaminoethyl)ether and
1,4-diazabicyclo[2.2.21]octane.
By including the amine salt of the present invention in the
polyurethane reaction mixture, the initiation of the foaming
reaction is delayed. Time to full cure, however, is not adversely
affected. Furthermore, several surprising results are obtained when
using the disclosed amine salts for making flexible foams using the
one-shot foaming process. Certain unexpected advantages realized
upon using the amine salts of hydroxy-acids include: significant
reduction in the force required to open the cells of flexible foams
by mechanical crushing; reduced foam shrinkage; a reduction in the
amine vapors given off by the foams and a lower corrosivity towards
metals than exhibited by amine salts made with the commonly used
carboxylic acids.
The amine salts of the tertiary amines and the hydroxy-acids can be
prepared simply by mixing the amine and the acid in a suitable
solvent. The amine salts of the hydroxy-acids are rather insoluble
in many common liquids and the best solvent identified for such
preparations is water. The hydroxy-acid also may be added to the
resin premix consisting of all the formulation components except
the polyisocyanate for in situ formation of the amine salt in the
resin. The addition of the amine salt of the hydroxy-acid to a
resin formulation may result in a solution or a stable dispersion.
Neutralization of the tertiary amine in the resin premix by the
hydroxy-acid is a fast process and the resulting catalytic
performance typically is the same as when a preformed salt is added
to the resin premix.
Depending on the tertiary amine used in the formulation, the
quantity of hydroxy-acid reacted with the amine can be adjusted to
achieve the desired reactivity and reactivity profile during
polyurethane formulation. Typically, desired catalyst compositions
will contain both free amine and bound amine in the form of the
amine salt of the hydroxy-acid. Based on acid-base equivalents, the
amount of the amine salt generally will be between about 2% to 95%
of the total amine equivalents in the formulation. A preferred
quantity of amine present as the salt in a resin formulation
typically will be between about 2% and 75% of the total tertiary
amine content on an equivalents basis and still more preferably,
between about 5% and 50%.
Polyols which are useful in the process of the invention for making
a polyurethane via the one-shot foaming procedure are any of the
types presently employed in the art for the preparation of flexible
slabstock foams, flexible molded foams, semi-flexible foams, and
rigid foams. The polyols normally can have hydroxyl numbers in the
range of about 10 to about 600. The hydroxyl numbers are preferably
between about 15 to about 85 for flexible foams and between about
250 and 500 for rigid foams. The hydroxyl number is defined by the
equation: ##EQU1## where: OH #=hydroxyl number of the polyol.
f functionality, that is, the average number of hydroxyl groups per
molecule of polyol.
m.w=number average molecular weight of the polyol.
For flexible foams the preferred functionality of the polyols is 2
to 4 and most preferably 2.3 to 3.5. For rigid foams the preferred
functionality is 2 to 8 and most preferably 3 to 5.
Polyols which can be used in the process of the present invention,
either alone or in admixture, can be of the following non-limiting
classes:
a) alkylene oxide adducts of polyhydroxyalkanes;
b) alkylene oxide adducts of non-reducing sugars and sugar
derivatives;
c) alkylene oxide adducts of phosphorous and polyphosphorous
acids;
d) alkylene oxide adducts of polyphenols;
e) alkylene oxide adducts of primary and secondary amines.
For flexible foams, a preferred class of alkylene oxide adducts of
polyhydroxyalkanes are the ethylene oxide and propylene oxide
adducts of trihydroxyalkanes. For rigid foams, the preferred class
of alkylene oxide adducts are the ethylene oxide and propylene
oxide adducts of ammonia, toluene diamine, sucrose, and
phenol-formaldehyde-amine resins (Mannich bases).
Polymer polyols are used extensively in the production of flexible
foams and are a preferred class of polyols useful in the process of
this invention. Polymer polyols are polyols which contain a stable
dispersion of a polymer, for example in the polyols a) to e) above
and more preferably the polyols of type a). Other polymer polyols
useful in the process of this invention are polyurea-polyols and
polyoxamate-polyols.
The polyisocyanates which are useful in the process of this
invention are organic compounds that contain at least two
isocyanate groups. Suitable organic polyisocyanates include the
hydrocarbon diisocyanates, (e.g. the alkylenediisocyanates and the
arylene diisocyanates) as well as known triisocyanates and
polymethylene poly(phenylene isocyanates) also known as polymeric
MDI. For flexible and semi-flexible foams, the preferred
isocyanates generally are: mixtures of 2,4-tolylene diisocyanate
and 2,6-tolylene diisocyanate (TDI) in proportions by weight of 80%
and 20% respectively and also 65% and 35% respectively; mixtures of
TDI and polymeric MDI, more preferably in the proportion by weight
of 80% TDI and 20% of crude polymeric MDI and 50% TDI and 50% crude
polymeric MDI; and all polyisocyanates of the MDI type. For rigid
foams, the preferred isocyanates are: polyisocyanates of the MDI
type and more preferably crude polymeric MDI.
The amount of polyisocyanate included in the foam formulations used
relative to the amount of other materials in the formulations is
described in terms of "Isocyanate Index". "Isocyanate Index" means
the actual amount of polyisocyanate used divided by the
theoretically required stoichiometric amount of polyisocyanate
required to react with all the active hydrogen in the reaction
mixture multiplied by one hundred (100) [see Oertel, Polyurethane
Handbook, Hanser Publishers, New York, N.Y. (1985)]. The Isocyanate
Indices in the reaction mixtures used in the process of this
invention generally are between 80 and 140. More usually, the
Isocyanate Index is: for flexible slabstock foams, typically
between 85 and 120; for TDI moulded foams, normally between 90 and
110; for MDI moulded foams, most often between 80 and 100; and for
rigid foams, generally between 90 and 130. Some examples of
polyisocyanurate rigid forms are produced at indices as high as
250-400.
Water often is used as a blowing agent in both flexible and rigid
foams. In the production of flexible slabstock foams, water
generally can be used in concentrations of between 2 to 7 parts per
hundred parts of polyol (phpp), and more often between 3.5 to 5.5
phpp. Water levels for TDI molded foams normally range from 2 to 6
phpp, and more often between 3 to 5 phpp. For MDI molded foam, the
water level is more normally between 2.5 and 4 phpp. Rigid foam
water levels range from 0.5 to 5 parts, and more often from 0.5 to
1 phpp.
Blowing agents based on volatile hydrocarbons or halogenated
hydrocarbons can also be used in the production of polyurethane
foams in accordance with the present invention. A significant
proportion of the rigid insulation foam produced is blown with
halogenated hydrocarbons. The preferred organic blowing agents for
rigid foams are the halogenated hydrocarbons, and more preferably
the hydrochlorofluorocarbons (HCFC) and the chlorofluorocarbons
(CFC). In the production of flexible slabstock foams, water is the
main blowing agent, however, organic blowing agents can be used as
auxiliary blowing agents. For flexible slabstock foams, the
preferred auxiliary blowing agents are the CFC's and
chlorohydrocarbons, and more preferably trichloromonofluorocarbon
(CFC 11) and dichloromethane (methylene chloride).
Flexible molded foams typically incorporate less auxiliary blowing
agents than slabstock foams although when used the preferred
auxiliary blowing agent is CFC 11. The quantity of blowing agent
varies according to the desired foam density and foam hardness as
recognized by those skilled in this art. The amount of
hydrocarbon-type blowing agents used varies between about 2 to 60
parts per hundred parts of polyol (phpp).
Catalysts that can be used for the production of polyurethanes in
addition to the amine-hydroxy acid salts of the present invention
include tertiary amines of both the non-reactive (fugitive) and
reactive types. Reactive amine catalysts are compounds which
contain one or more active hydrogens and, as a consequence, can
react with the isocyanate and be chemically bound in the
polyurethane polymer matrix. For the production of flexible
slabstock and molded foams, the preferred amine catalysts are
bis(N,N-dimethylaminoethyl)ether and 1,4-diazabicyclo[2.2.2]octane.
For the production of rigid foams, the preferred amine catalysts
are dimethylcyclohexylamine (DMCHA) and dimethylethanolamine
(DMEA).
Organo-metallic catalysts or metal salt catalysts also can and
often are used in polyurethane foam formulations. For flexible
slabstock foams, the generally preferred metal salt and
organo-metallic catalysts are stannous octoate and
dibutyltindilaurate respectively. For flexible molded foams, the
normally preferred organo-metallic catalysts are:
dibutyltindilaurate; and dibutyltindialkylmercaptide. For rigid
foams the most often preferred metal salt and organo-metallic
catalysts are potassium acetate, potassium octoate and
dibutyltindilaurate, respectively. Metal salt or organo-metallic
catalysts normally are used in small amounts in polyurethane
formulations, typically from about 0.001 phpp to about 0.5
phpp.
Crosslinkers also may be used in the production of polyurethane
foams. Crosslinkers are typically small molecules, usually less
than 350 gram molecular weight, which contain active hydrogens for
reaction with the isocyanate. The functionality of a crosslinker is
greater than 3 and preferably between 3 and 5. The amount of
crosslinker used can vary between about 0.1 phpp and 20 phpp and
the amount used is adjusted to achieve the required foam
stabilization or foam hardness. Examples include glycerine,
diethanolamine, triethanolamine and
tetrahydroxyethylethylenediamine.
Silicone surfactants which may be used in the process of this
invention include: "hydrolysable" polysiloxane-polyoxyalkylene
block copolymers; "non-hydrolysable" polysiloxane-polyoxyalkylene
block copolymers; cyanoalkylpolysiloxanes; alkylpolysiloxanes;
polydimethylsiloxane oils. The type of silicone surfactant used and
the amount required depends on the type of foam produced as
recognized by those skilled in the art. Silicone surfactants can be
used as such or dissolved in solvents such as glycols. For flexible
slabstock foams the reaction mixture usually contains from 0.3 to 4
phpp of silicone surfactant, and more often from 0.7 to 2.5 phpp.
For flexible molded foam the reaction mixture usually contains 0.1
to 5 phpp of silicone surfactant, and more often 0.5 to 2.5 phpp.
For rigid foams the reaction mixture usually contains 0.1 to 5 phpp
of silicone surfactant, and more often from 0.5 to 3.5 phpp.
Temperatures useful for the production of polyurethanes varies
depending on the type of foam and specific process used for
production as well understood by those skilled in the art. Flexible
slabstock foams are usually produced by mixing the reactants
generally at an ambient temperature of between about 20.degree. C.
to 40.degree. C. The conveyor on which the foam rises and cures is
essentially at ambient temperature, which temperature can vary
significantly depending on the geographical area where the foam is
made and the time of year. Flexible molded foams usually are
produced by mixing the reactants at temperatures between 20.degree.
C. and 30.degree. C., and more often between 20.degree. C. and
25.degree. C. The mixed starting materials are fed into a mold
typically by pouring. The mold preferably is heated to a
temperature between about 35.degree. C. and 70.degree. C., and more
often between about 40.degree. C. and 65.degree. C. Sprayed rigid
foam starting materials are mixed and sprayed at ambient
temperature. Molded rigid foam starting materials are mixed at a
temperature in the range of 20.degree. C. to 35.degree. C. The
process used for the production of flexible slabstock foams, molded
foams, and rigid foams in accordance with the present invention is
the "one-shot" process where the starting materials are mixed and
reacted in one step.
The basic procedure used to mix the foams for the laboratory
evaluations reported hereinafter are:
1. The formulation ingredients are weighed in preparation for
sequential addition to an appropriate mixing container.
2. The polyol(s), water, amine catalyst(s), silicone surfactant(s),
and crosslinkers (if any) are mixed thoroughly followed by a
"degassing" step of prescribed time. After the "degassing" step,
additional ingredients can be added such as: an auxiliary blowing
agent(s) (if used); and any metal salt catalyst(s) which are
sensitive to hydrolysis.
3. The polyisocyanate is added and mixed with the "degassed"
ingredients. Specific procedures for the production of slabstock
foam and molded foam vary and are summarized as follows:
a) Flexible Molded Foam
Premixes are prepared by weighing the required amounts of polyols,
water, crosslinker (diethanolamine), silicone surfactant, and amine
catalysts into 2 liter mixing cups. The mixing is done with a 6
blade centrifugal mixing impeller driven at 3400 rpm with a drill
press. A stainless steel baffle system is added to the mixing cup
to assure high quality mixing. The total mixing process takes
approximately 1.5 minutes. The premix is stirred for 1 minute, then
allowed to "degas" for 15 seconds, and the pre-weighed quantity of
isocyanate is added 7 seconds before the end of the mixing
process.
Foam pads are molded in a 38.times.38.times.13 cm cast aluminum
mold equipped with four 3.2 mm(1/8 in) vent orifices in the cover.
Mold release (Chem-Trend RCT-B1208) is applied to the mold which
then is preheated to about 75.degree. C. in an oven. After the mold
is removed from the oven, it is allowed to cool to about 69.degree.
C. at which time the mixing process begins. This results in the
foaming mixture being poured into the mold at a temperature of
about 65.degree..+-.1.degree. C. The mold is returned to the oven
90 seconds after pour and removed just before demold which is
performed at 6 minutes.
b) Flexible Free-Rise (Slabstock) Foam
Slabstock foam is made in a manner similar to that used in
preparing the molded foam. The foaming mixture is poured into a 5
gallon pail and allowed to rise freely.
Test methods used to measure the physical characteristics of the
foam produced in the examples are as follows:
______________________________________ Physical Characteristic Test
Method ______________________________________ Density ASTM D 3574
Test A Elongation ASTM D 3574 Test E IFD ASTM D 3574 Test B1
Tensile ASTM D 3574 Test E Strength Tear Resistance ASTM D 3574
Test F Porosity ASTM D 3574 Test G (Air Flow) Compression Set as
received ASTM D 3574 Test I.sub.1 humid aging ASTM D 3574 Test J
except conditions: 6h @ 105.degree. C. Exit Time Exit time is the
time elapsed, in seconds, from the end of the mixing process to the
first appearance of foam extrusion from any of the four vents of
the mold. Force-to-Crush Force-to-crush (FTC) is the peak force
required to deflect a foam pad with the standard 323 cm.sup.2
indentor, 1 minute after demold, to 50% of its original thickness.
It is measured with a load testing machine using the same setup as
that used for measuring foam hardness. A load tester crosshead
speed of 50.8 cm/minute is used.
______________________________________ The terms and abbreviations
used in the following examples have the following meaning: Term or
Abbreviation Meaning ______________________________________ Polyol
A A polyalkylene oxide triol, produced propylene- oxide and
ethylene oxide and glycerine having a hydroxyl number of about 35
mg KOH/g. The ethylene oxide is present primarily in blocks as a
cap for the triol. Polyol B A polymer polyol based on Polyol A,
containing a stable dispersion of acrylonitrile/styrene copolymer,
with a hydroxyl number of about 21 mg KOH/G. Polyol C A
polyalkylene oxide triol, produced from propy- lene oxide and
ethylene oxide and glycerine with the ethylene oxide as an internal
block and having a hydroxyl number of about 58. K-1
bis(N,N-dimethylaminoethyl)ether K-2 1,4-diazabicyclo[2.2.2]-octane
A-1 Formic acid A-2 2,-ethylhexanoic acid HA-1 bis
2-hydroxymethylpropionic acid HA-2 citric acid HA-3
dihydroxybenzoic acid HA-4 glycolic acid HA-5 salicylic acid HA-6
tartaric acid M-1 Stannous octoate S-1 A silicone surfactant sold
for use in high resiliency foam by OSi Specialties Incorporated as
"Y-10366" S-2 A silicone surfactant sold for use in conventional
slabstock foam by OSi Specialties Incorporated as "L-620" BA-1
Dichloromethane (methylene chloride) TDI A mixture of 80 wt. % of
2,4-tolylene diisocyanate and 20 wt. % 2,6-tolylene diisocyanate
DEOA Diethanolamine KOH Potassium hydroxide g grams mg milligrams s
seconds min minute kg kilograms kPa kiloPascal m meter cm
centimeter mm millimeter ft foot % percent by weight phpp parts per
hundred parts by weight of polyol ppm part per million parts by
weight .degree.C. degree Celsius N Newton meq milliequivalent FTC
Force-to-crush (crushing force)
______________________________________
While the scope of the present invention is defined by the appended
claims, the following examples illustrate certain aspects of the
invention and, more particularly, describe methods for evaluation.
The examples are presented for illustrative purposes and are not to
be construed as limitations on the present invention.
EXAMPLES 1-11
Water, DEOA, amine catalysts K-1 and K-2, and acids A-1 or HA-1
were mixed together as a premixed component. For the foams of
Examples 2, 3, and 4, the acid was added to the catalyst K-1 before
preparation of the premix. For the foam of Example 5, the acid was
added to the catalyst K-2 prior to premix preparation. The reaction
mixture was mixed and foamed as summarized above. The exit time and
the force-to-crush were measured using the procedure described
above.
The formulations used and the results obtained are shown in Tables
1 and 2. These formulations are typical for HR (high resilience)
molded foam for automotive seating. The formulations in Table 1 are
high water and low polymer polyol content (low solids) systems
representative of that used for the production of seat-backs. All
foams in this Table contain the same quantity of amine catalysts,
K-1 and K-2. The foam of Example 1 contains no acid blocker and is
the reference (control) foam. The foam of Example 2 contains formic
acid. The foams of Examples 3-5 are illustrative of the present
invention and contain bis(hydroxymethyl)propionic acid (DMPA) at
various concentrations. The reaction is delayed by the use of the
amine salt of the hydroxy-acid. These examples show the effect of
the hydroxy-acid on the foam exit-time and crushing force (FTC). In
the case of the foam of Example 5, the reaction delay is not
evident because the amine blocked by the acid in this case is the
so-called cure catalyst (K-2), rather than the blow catalyst (K-1).
Blocking the cure catalyst has less of an impact on the foam rise
time, which is a blow-reaction controlled process.
The lower crushing force of Examples 3-5 relative to Examples 1 and
2 shows that the cells of the foam made according to the process of
the present invention are either more open or more easily opened or
both. Industry and laboratory experience shows that there is a
direct correlation between the mechanical force required to "crush"
a foam and the shrinkage that the foam undergoes if not crushed.
Consequently, foams exhibiting significantly reduced FTC's
statistically shrink less.
The formulations in Table 2 are representative of those used for
the production of seat-cushions. The same results and effects
observed in Table 1 can also be seen in the results reported in
Table 2. Examples 6 and 7 are the controls, while Examples 8-11
illustrate the invention. For the foams of Examples 9, 10, and 11,
catalyst K-2 was blocked with DMPA prior to preparation of the
water-amine premix.
TABLE 1
__________________________________________________________________________
Formulation, phpp Examples 1 2 3 4 5*
__________________________________________________________________________
Polyol A 75 75 75 75 75 Polyol B 25 25 25 25 25 Water 4.2 4.2 4.2
4.2 4.2 DEOA 1.5 1.5 1.5 1.5 1.5 Catalyst K-1 0.07 0.07 0.07 0.07
0.07 Catalyst K-2 0.117 0.117 0.117 0.117 0.117 Acid A-1 -- 0.030
-- -- -- Hydroxy-acid -- -- 0.029 0.059 0.022 HA-1 Surfactant 1.0
1.0 1.0 1.0 1.0 S-1 TDI 80/20 52.2 52.2 52.2 52.2 52.2 Index 105
105 105 105 105 Density, kg/m.sup.3 29.7 20.6 29.6 30.4 30.3 Exit
Time, s 35 39 43 46 34 FTC, N/323 cm.sup.2 1068 1163 623 267 614
__________________________________________________________________________
TABLE 2
__________________________________________________________________________
Formulation, phpp Examples 6 7 8 9 10* 11
__________________________________________________________________________
Polyol A 50 50 50 50 50 50 Polyol B 50 50 50 50 50 50 Water 3.5 3.5
3.5 3.5 3.5 3.5 DEOA 1.3 1.3 1.3 1.3 1.3 1.3 Catalyst K-1 0.07 0.07
0.07 0.07 0.07 0.07 Catalyst K-2 0.10 0.10 0.10 0.10 0.10 0.10 Acid
A-1 -- 0.030 -- -- -- -- Hydroxy-acid HA-1 -- -- 0.029 0.019 0.024
0.028 Surfactant S-1 1.0 1.0 1.0 1.0 1.0 1.0 TDI 80/20 44.1 44.1
44.1 44.1 44.1 44.1 Index 105 105 105 105 105 105 Density,
kg/m.sup.3 33.4 33.5 34.3 33.5 34.6 34.8 Exit Time, s 45 48 49 50
51 51 FTC, N/323 cm.sup.2 770 792 329 391 289 236
__________________________________________________________________________
EXAMPLES 12-14
The foams of these examples were prepared in the same way as those
of Examples 1-11. However, the foams were subjected to a 30 minute
post-cure at 120.degree. C. after demold. Examples 12 and 13 are
controls, while Example 14 is made in accordance with the present
invention. The foam pads were conditioned, cut, and tested
according to ASTM 3574. The results of the physical property tests
are reported in Table 3. As shown, use of the hydroxy-acid results
in a significant improvement in the tear resistance of the foam and
also an increase in the foam's IFD values. No detrimental effect on
any foam properties is observed.
TABLE 3 ______________________________________ Formulation, phpp
Examples 12 13 14 ______________________________________ Polyol A
75 75 75 Polyol B 25 25 25 Water 3.5 3.5 3.5 DEOA 1.3 1.3 1.3
Catalyst K-1 0.07 0.07 0.07 Catalyst K-2 0.10 0.10 0.10 Acid A-1 --
0.030 -- Hydroxy-acid HA-1 -- -- 0.029 Surfactant S-1 1.0 1.0 1.0
TDI 80/20 44.2 44.2 44.2 Index 105 105 105 Density, kg/m.sup.3 33.7
34.2 34.5 Exit Time, s 50 52 54 Porosity, scfm/ft.sup.2 27.8 31.8
23.3 IFD, N/323 cm.sup.2 @ 25% deflection 129 136 153 @ 65%
deflection 307 325 358 Load Ratio 2.38 2.39 2.33 25% return, % 86
85 84 Tensile Strength, kPa 102 108 114 Elongation, % 104 110 111
Tear Resistance, N/m 217 226 249 Compression Set, % As received,
C.sub.d @ 50% deflection 10.6 10.3 10.3 @ 75% deflection 9.3 9.2
9.2 Humid aged, C.sub.d (6h @ 105.degree. C.) @ 50% deflection 26.6
27.3 25.4 ______________________________________
EXAMPLES 15 AND 16
The results of a comparative corrosion study performed with acid
A-1 and hydroxy-acid HA-1 are reported in Table 4. The testing was
done according to ASTM method G31-72(82). Aqueous solutions 15 and
16 were prepared and used to measure their corrosivity to steel.
Three pairs of exposure jars were set-up in order to get corrosion
measurements at three different exposure durations, 14, 28, and 119
days. Corrosion was measured by percent weight loss of sample in
grams. The results demonstrate that the DMPA amine salt is much
less corrosive to steel than the formic acid amine salt.
TABLE 4 ______________________________________ Solution Examples 15
16 ______________________________________ Water, % 51.3 38.2
Catalyst K-1, % 26.3 23.7 Acid A-1, % 11.3 -- Acid-A-1, meq/g 2.46
Hydroxy-acid HA-1, % -- 38.2 Hydroxy-acid HA-1, meq/g -- 2.84
Dipropylene glycol, % 11.2 -- Corrosion, Steel after 14 days,
weight loss, % 0.491 0.051 qualitative evaluation rust in vapor no
attack space, etched in liquid after 28 days, weight loss, % 2.847
0.447 qualitative evaluation rust in vapor no attack space, etched
in liquid after 119 days, weight loss, % 10.355 0.001 qualitative
evaluation rust in vapor no attack space, heavily etched in liquid,
liquid has turned black ______________________________________
EXAMPLES 17-20
Amine vapors given off by foams made without any added acid, made
with formic acid, made with 2-bis (hydroxymethyl) propionic acid,
and made with 2ethylhexanoic acid were measured. Two methods were
employed to obtain this measurement: 1) the amine level in the air
space over freshly made foam was determined using the Drager tube
method; and 2) the amine vapors released from foam after it has
cured and cooled was studied by a head-space gas chromatographic
(GC) technique.
For the Drager tube method, the amount of urethane foam reaction
mixture was adjusted so that it filled about two thirds of a 5
gallon container once the reaction was completed. The reaction
mixture was mixed, added to a container fitted with a polyethylene
seal, and the foam allowed to rise. Just after blow-off, a small
cut was made in the seal and a Drager tube (Amine Test, #8101061)
on a Model 31 Drager hand pump was inserted at just above the level
of the foam. A gas sample was taken, the tube removed and the cut
sealed with tape. Additional gas samples were taken at various time
intervals. The length of color change of the tube is indicative of
the quantity of amine present in the air space above the foam. The
reduction in amine vapor given off by fresh foam when the dihydroxy
acid is used is shown by the results in Table 5 (Amines, by Drager
tube).
The amine vapors given off as the foam is heated were analyzed
using a head space gas chromatographic (GC) method. Samples of each
foam were sealed into bottles and the individual bottles heated to
70, 100, and 130.degree. C. for 1, and 2 hours respectively. The
vapors in the bottles were sampled and analyzed by GC for amine
content (catalyst K-1). The foam of Example 19, made with the
hydroxy-acid (DMPA) is shown to release significantly less amine
vapor at any given temperature. This result is obtained despite the
fact that this foam contains an elevated level of potentially
"extractable" amine.
TABLE 5 ______________________________________ Formulation, phpp
Examples 17 18 19 20 ______________________________________ Polyol
C 100 100 100 100 Water 5.5 5.5 5.5 5.5 Catalyst K-1 0.053 0.050
0.051 0.050 Acid A-1 -- 0.021 -- -- Acid A-2 -- -- -- 0.089
Hydroxy-acid HA-1 -- -- 0.085 -- Catalyst M-1 0.23 0.23 0.23 0.23
Surfactant S-2 1.0 1.0 1.0 1.0 Blowing agent BA-1 10 10 10 10 TDI
80/20 66.3 66.3 66.3 66.3 Index 107 107 107 107 Cream time, s 19 21
24 19 Blow-off time, s 123 130 130 114 Maximum height, cm 23.1 23.7
24.5 24.3 Top collapse, cm 0.22 0.22 0.21 0.22 Amines, by Drager
Tube @ t = 0 min., mm 8 10 4-5 6-7 @ t = 10 min., mm 4 4 0-1 2-3 @
t = 20 min., mm 1 1 0 0-1 Amine (liquid extraction) Catalyst K-1,
ppm 165 231 222 156 Amine (headspace analysis) @ 70.degree. C. for
1 h (K-1), ppm 3.5 3.7 0.6 0.6 @ 100.degree. C. for 1 h (K-1), ppm
45 50 5.3 12 @ 130.degree. C. for 2 h (K-1), ppm 70 103 26.5 34.3
______________________________________
EXAMPLES 21-26
Formulations using several different amine salt catalysts were
mixed and tested using the same procedures described in connection
with Examples 1-11. Formulation 21 does not use any hydroxy-acid
catalyst and serves as a control. Hydroxy-acids HA-2, -3, -4, -5,
and -6 are representatives of hydroxy-acids of the present
invention. The quantity of hydroxy-acid, in equivalents, is the
same for each of the hydroxy-acids used. The lower crushing force
resulting from the use of the hydroxy-acids in the formulations in
shown in Table 6.
TABLE 6
__________________________________________________________________________
Formulation, phpp 21 22 23 24 25 26
__________________________________________________________________________
Polyol A 75 75 75 75 75 75 Poylol B 25 25 25 25 25 25 Water 4.2 4.2
4.2 4.2 4.2 4.2 DEOA 1.5 1.5 1.5 1.5 1.5 1.5 Catalyst K-1 0.07 0.07
0.07 0.07 0.07 0.07 Catalyst K-2 0.117 0.117 0.117 0.117 0.117
0.117 Hydroxy-acid HA-2 -- 0.020 -- -- -- -- Hydroxy-acid HA-3 --
-- 0.047 -- -- -- Hydroxy-acid HA-4 -- -- -- 0.023 -- --
Hydroxy-acid HA-5 -- -- -- -- 0.042 -- Hydroxy-acid HA-6 -- -- --
-- -- 0.023 Surfactant S-1 1.0 1.0 1.0 1.0 1.0 1.0 TDI 80/20 51.9
51.9 51.9 51.9 51.9 51.9 Index 105 105 105 105 105 105 Density,
kg/m.sup.3 30.1 30.6 30.4 30.5 30.3 30.7 Exit Time, s 33 32 36 35
35 34 FTC, N/323 cm.sup.2 1200 660 420 570 430 760
__________________________________________________________________________
The delayed-action catalysts of the present invention are simple
amine salts of tertiary amines and carboxylic acids, wherein the
carboxylic acids contain hydroxyl functional groups
(hydroxy-acids). The hydroxy-acids contain a hydrocarbon moiety,
particularly linear or branched aliphatic and/or aromatic
hydrocarbon moieties, having one (1) or more hydroxyl group(s) and
one (1) or more carboxylic acid group(s). Preferred hydroxy-acids
will have 2 to 3 hydroxyl groups and 1 to 2 carboxylic acid groups.
Suitable hydroxy-acids include: bis 2-hydroxymethylpropionic acid
(dimethylolpropionic acid); citric acid; salicylic acid, glycolic
acid and the like.
The principles, preferred embodiments and modes of operation of the
present invention have been described in the foregoing
specification. The invention which is intended to be protected
herein, however, is not to be construed as limited to the
particular forms disclosed, since they are to be regarded as
illustrative rather than restrictive. Variations and changes may be
made by those skilled in the art without departing from the spirit
of the invention.
* * * * *